Along with the rapid development and availability of portable electronic products, demand for lithium-ion (Li-ion) secondary batteries is increasing due to their remarkable advantages, such as light weight, high operating voltage, high energy density, long service life and so on. In addition, Li-ion secondary batteries are more environmentally friendly when compared to nickel-cadmium, nickel-hydrogen and nickel-zinc batteries and are touted as the leading candidate for development of flexible batteries.
Among various cathode materials, the class of layered composite oxides, expressed as xLi2MnO3.(1−x)Li(NiMn)O2 (LMO), has drawn escalated attention due to their high capacities beyond 250 mAh/g. This class of cathode materials may produce a theoretical specific energy of above 1000 Wh/kg, much higher than that of LiMn2O4, LiFePO4 and Li[NiCoMn]O2.
In addition to the inherent properties of materials per se, the microstructure of materials can have an impact on the performance of batteries, such as energy density and discharge power. Moreover, the crystal structure of the material powder is influential to the migration of lithium ions during battery charge/discharge. The migration of lithium ions usually occurs at crystal planes (101) and (104), while the diffusion of lithium ions usually occurs at crystal plane (103), which makes it possible to alter the crystal lattice to increase the space for lithium ion migration. There remains a need in the art to improve the cathode materials in various aspects to improve performance of Li-ion batteries (also referred to as “Li batteries”).